Hydrogen sulfide-induced enhancement of gastric fundus smooth muscle tone is mediated by voltagedependent potassium and calcium channels in mice

AIM:To investigate the effect of hydrogen sulfide(H2S)on smooth muscle motility in the gastric fundus.METHODS:The expression of cystathionineβ-synthase(CBS)and cystathionineγ-lyase(CSE)in cultured smooth muscle cells from the gastric fundus was examined by the immunocytochemistry technique.The tension of the gastric fundus smooth muscle was recorded by an isometric force transducer under the condition of isometric contraction with each end of the smooth muscle strip tied with a silk thread.Intracellular recording was used to identify whether hydrogen sulfide affects the resting membrane potential of the gastric fundus in vitro.Cells were freshly separated from the gastric fundus of mice using a variety of enzyme digestion methods and whole-cell patch-clamp technique was used to find the effects of hydrogen sulfide on voltage-dependent potassium channel and calcium channel.Calcium imaging with fura-3AM loading was used to investigate the mechanism by which hydrogen sulfide regulates gastric fundus motility in cultured smooth muscle cells.RESULTS:We found that both CBS and CSE were expressed in the cul tured smooth muscle cel ls from the gastric fundus and that H2S increased the smooth muscle tension of the gastric fundus in mice at low concentrations.In addition,nicardipine and aminooxyacetic acid(AOAA),a CBS inhibitor,reduced the tension,whereas Nω-nitro-L-arginine methyl ester,a nonspecific nitric oxide synthase,increased the tension.The AOAA-induced relaxation was significantly recovered by H2S,and the Na HS-induced increase in tonic contraction was blocked by 5 mmol/L4-aminopyridine and 1μmol/L nicardipine.Na HS significantly depolarized the membrane potential and inhibited the voltage-dependent potassium currents.Moreover,Na HS increased L-type Ca2+currents and caused an elevation in intracellular calcium([Ca2+]i).CONCLUSION:These findings suggest that H2S may be an excitatory modulator in the gastric fundus in mice.The excitatory effect is mediated by voltagedependent potassium and L-type calcium channels.

Nitric oxide and hydrogen sulfide share regulatory functions in higher plant events

Nitric oxide(NO)and hydrogen sulfide(HS)are two molecules that share signaling properties in plant and animal cells NO and H2S originate two farmilies of de rived mol ecules designated reactive nitrogen and sulfur species(RNS and RSS,respectively).These molecules are responsible for certain protein regulatory processes through posttranslational modifications(PTMs),being the most remarkable S nitrosation and persufidation,which afect the thiol group of cysteine residues.NO and H2S can also exert regulatory functions due to their interaction through the iron present in proteins that contain heme groups or iron-sulfur dlusters,as reported mainly in animal cells.Howewer,the available information in plant cells is still very limited thus far.In higher plants,NO and H2S are involved in a myriad of physiological events from seed germination to fruit ripening,but also the mec hanism of response to biotic and abiotic stress conditions.This vie wpoint manuscript highlights the functional regulatory parllelism of these two molecules which also interact with the metabolism of reactive oxygen species(ROS)in plant cells.